煤基重金属螯合吸附剂的制备及性能研究

为提高煤对重金属离子的吸附性能，以平均粒度为71.55 μm的神府煤颗粒为原料，γ-氨丙基三乙氧基硅烷（KH550）为偶联剂，将三乙烯四胺（TETA）通过偶联剂接枝于煤粉颗粒表面，与二硫化碳、氢氧化钠反应生成二硫代氨基甲酸盐制得以神府煤为基体的重金属螯合吸附剂，考察了其对重金属离子Ni2+的螯合吸附特性。结果表明，螯合吸附剂对Ni2+的螯合吸附符合Langmuir吸附等温线，其吸附容量为104.17 mg/g，明显高于原煤粉的32.23 mg/g。螯合吸附剂吸附Ni2+的ΔH，ΔG均为负值，说明吸附为自发放热过程。红外光谱分析表明，螯合吸附剂在1 309 cm-1及1 120 cm-1吸收峰为N-C-S，CS的吸收峰，表明DTC螯合基团成功接枝到煤颗粒表面。吸附饱和的螯合吸附剂在较高pH值条件下具有较好的稳定性。用0.1 mol/L醋酸脱附吸附饱和的螯合吸附剂，脱附率达90.74%。

Preparation and performance of coal based chelating adsorbent

In order to improve the adsorption capacities of coal for heavy metal ions，triethylenetetramine was grafted on the surface of Shenfu coal particles with 71.55 μm average diameter using γ-aminopropyltriethoxysilan as the coupling reagent.Then the grafted coal particles reacted with carbon disulfide and sodium hydroxide to form dithiocarbamate on the surface of coal particles.The adsorptive properties and mechanism of Ni2+ onto coal based chelating adsorbent were investigated.The results show that the adsorption isotherm of Ni2+ onto coal based chelating adsorbent can be described by Langmuir model.The adsorption capacity of Ni2+ onto coal based chelating adsorbent is 104.17 mg/g，which is founded to be much higher than that of original coal of 32.23 mg/g.The negative values of ΔH and ΔG illustrate the process is spontaneous and exothermic.FTIR spectrum analysis illustrate that the dithiocarbamate is grafted onto the surface of the coal particles successfully and reacte with Ni2+ from the aqueous solution.The saturated chelating adsorbent is stable at higher pH.The desorption rate of the saturation chelating adsorbent for Ni2+ can reach to 90.74% by 0.1 mol/L acetic acid.